SciFinder indexes millions of documents from the late 19th century up to last week that may contain desired physical property information. It's the best index to start this kind of search, but it helps if you first understand the database's scope, structure, and limitations, and learn some handy tips to get better results.

SciFinder is not a purely relational database in the same way that Reaxys is. This means that, in the bibliographic record that describes the document, the substance identifier(s) are not always related (in the structural sense) to data about that substance that may be present in the indexed document. Relevance can be imprecise, because all the concepts you're looking for may be present in a record, but they may not be in the desired context. Here's a sample record:

Click to zoom.

If the data in question was the main topic of the article, values may even be shown in the abstract (check the source anyway). But if the document just noted the data in passing, the abstract and indexing may give no indication of its presence, and your search will not find it. Trying a search several different ways can reduce uncertainty.

Older literature can be problematic. The quality and consistency of Chemical Abstracts' human indexing varied over the years, and was generally less thorough and granular before 1970. Unfortunately, that was when a lot of fundamental data was reported. When CAS converted the pre-1967 years of CA to digital format, the Registry Number for a substance was algorithmically assigned to the article record ONLY if the original Subject Index for that period included a reference to the article under the substance's CA Index Name. In many cases, CA abstracters only made this assignment when the substance was the main focus of the document, omitting other compounds that may have been mentioned. (The conversion project made no attempt to re-analyze or re-index the original literature.) Searching by common name (see second example below) instead of RN occasionally yields some articles where the name appears in the title or abstract but was not specifically indexed by RN.

1. Start with the Explore References: Research Topic query using a property name with the substance's Registry Number or common name.

Use the RN as a search term in place of a chemical name. Your search will be more precise by avoiding name-fragment hits that are not directly related to the compound you're seeking.

If the property index term contains a connector, such as OF in "Heat OF formation," omit the connector from your query.

SciFinder automatically includes certain synonyms and plurals in your search. For example, heat = enthalpy and both terms will be retrieved by searching one of them.

The OF operator (not case-sensitive) causes SciFinder to look for records that contain both the property name and the RN anywhere in the record. You'll see a histogram from which you can select the references with the concepts "closely associated with one another" to increase precision. Using the AND operator just looks for the concepts anywhere in the record but doesn't offer the proximity option.

2. Name vs. Registry Number

When you use a chemical name instead of a RN, SciFinder tries to resolve the RN automatically if it can. This can be less precise than using a predetermined RN, but also helpful.

3. Starting from the Explore Substances Search

You can also start a search from the "Explore Substances" option. This search does essentially the same thing as above but with one extra step. First you search for a substance by Registry Number, molecular formula, name, or structure.

The Registry database in SciFinder also contains some experimental and predicted properties for substances (red arrow). Since we're talking about literature searching here, we'll pass over that option.

Click "Get References" and retrieve references from all years. (Note: Selecting "Properties" from the "roles" pop-up menu will retrieve only post-1967 references. The Properties role has not been retrospectively assigned to RNs before that date. Get all references if you think that the data you seek were possibly reported before that time.)

Finally, use the Refine tab to limit the results set using a property name.

When you use this method, "closely associated" proximity is not considered. This makes this method a bit less precise than the References search option shown above.

Other Tools

A free tool from NIST-TRC that allows you to search precisely for references reporting desired property and substance-level data within the NIST SOURCE Data Archive, and then generate a PDF literature report as required by a number of data-focused journals. The Archive covers reports of pure compounds and binary and ternary mixtures. (Polymers, materials with unspecified formulas, ions, and reaction properties are not included.) Note that the actual data is not provided in ThermoLit; that can often be found in the related Web Thermo Tables database.